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(N Modem 2 SheetsSheet 1.

D. DRAWBAUGH.

- WITNESSES v I INYENTOR N PETERS, Fhulo-Llthognpher, Washmgmn. 0. c.

(No Model.) 2 Sheets'$heet 2.

D. DRAWBAUGH.

TELEPHONE TRANSMITTER No. 297,579. Patented Apr. 29, 1884.

llHllll ITNE-SSES: INVBNTOR @vmua/uqa,

# ATTORNEYS N. PEYERS. .Photo-Lflhagrnphar, Wuhingtom 01c.

Ilnrrn rnrns DANIEL DRAXVBAUGH, OF EBERLYS MILL, PENNSYLVANIA, ASSIGNOE TO 4 THE PEOPLES TELEPHONE COMPANY, OF NEXV YORK.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 297,579, dated April 29, 1884. Application filed November I2, 1883. (No model.)

f will whom it may concern:

Be it known that I, DANIEL DRAWBAUGH, of Eberlys Mill, Cumberland county, Pemr sylvania, have invented a new and useful Im- 5 provement in Telephone Transmitters, of

which the following is a specification.

The invention consists in a telephone-transmitter containing electrodes influenced by the vibration of a diaphragm, so as to produce IO modifications in a current suitable for telephonic purposes, and also a vibrating 'ar-mature moved by the same vibrations of the same diaphragm in front of the core of an electro-magnet. In the particular construction herein described one electrode is attached to the rear side of the diaphragm and at or about its center. The second electrode is supported by a spring-piece of inductive materiahwhich spring-piece is polarized by a contact with a permanent magnet, and also forms the armature of the electromagnet. The core of the eleetro-magnet is polarized by contact with another and separate permanent magnet, and said eleetro-magnet is inclosed 2 in a secondary coil.

In the drawings, Figure 1 is a rear view of the instrument with a portion broken away, in order to show the arrangement of thebindingposts and adjusting devices. Fig. 2 is a hori- 0 zontal section on the line 00 00 of Fig. 1. Fig.

3 is a partial vertical section on the line y y of Fig. 1.

Similar letters of reference indicate like parts.

A is the box or case of the instrument.

B is the outer cover, containing the mouthpiece O. I here show the cover B in the form of a door hinged to the case A. This construction is not at all material, inasmuch as the cover B may be firmly attached by any convenient means to the box A, and not made hinged or movable.

D is the diaphragm, to the center of which I attach in any convenient way a small metal cup, E, holding an electrode, F. The second electrode, G, is held in a similar metal cup,

11, riveted or otherwise secured to the end of a flat spring, I, of conducting material. The spring I has the greater part of its length in contact with, and is suitably secured to, the

permanent magnet J. I purposely give the spring I a large area of contact with the magnet J in order to increase, so far as possible, the polarization of the free end of the sprin The free end of the spring I is disposed in frpnt of 5 5 oneend of the soft-iron core K of the electro magnet L. The other end of the core K is held by means of a screw, M, in close contact with one pole of the bent permanent magnet N 5 also connected to the same pole of the permanent magnet N is a bar, 0, of brass or other conducting material, the other end of which is connected to the case A of the instrument by means of an adj Listing-screw, P. The electro-. magnet L is in fact an induction-coil having a primary wire, to which the local-battery circuit passes, anda secondary wire, which collects the induced currents and conducts them to the line.

The various adj ustmenls of the instrument are effected by the following means: The electro-magnet or induction-coil L may be given a longitudinal motion by means of the screw P, communicating with the bar O. It will be seen that the permanent magnet N is connected by 7 5 screws to a wooden block, Q, and this block is hinged to the case A. Beneath the block Q is arranged a spring, It, which tends to throw the block Q upward, so moving the upper end of the magnet N and barO outward. Conse- 8o quently,when the screw 1? is turned in one direction, the action of the spring It moves the magnet N, bar 0, and electro-magnet L outward; and when the screw 1? is turned in the other direction it causes said parts to move inward in opposition to the action of the spring It. The object of this means of adjustment is to regulate the distance of the end of the core K from the end of the armature-spring I, and, by the degree of repulsion of the core and armao ture,to govern the initial pressure between the electrodes. As another and independent means of adjusting the initial pressure of the electrodes, Iprovide the following arrangement: Inside the case is secured a Hat spring, S, the 5 free arm of which presses upon the arm of the magnet J, to which arm the electrode carrying spring I is attached. The effect, therefore, of this spring S is to separate the electrodes, the magnet J turning,in such case,on its fastroe ening-screws T (dotted lines, Fig. 1) as a ful- Cllllll.

U is an adjusting-screw passing throughthe case A, and bearing against the permanent magnet J on the opposite side of the fulcrum. By turning this screw in one direction, the permanent magnet J is caused by the action of the spring S to turn on its fulcrum, and thus to move the spring I, so as to separate the electrodes D and G. Vhen the screw U is turned in the other direction, the magnet is so moved as to cause the electrodes to approach nearer together. Either or both of the above means of regulating the initial pressure between the electrodes may be employed at will. The circuits in the instrument are as follows: from the battery to the binding-posts 1, thence by the switclrlever V to the contactpoint a, thence by the wire I) to the primary of the inductioncoil or elcctro magnet L, thence by the wire a to the spring I, to the electrode G, electrode F, and thence by the wire (I to the binding-post 2, and so back to the battery. The secondary wires 0 e of the coil L are electrically connected with the line binding-posts 3 and 4, and with the posts 5 and 6, to which a receiving-telephone may be attached.

The operation of the instrument is as follows: When speech is uttered in front of the diaphragm, the vibrations of the latter communicated to the electrodes so move them as to cause said electrodes to produce modifications in the battery-current passing through them, by reason of which modifications the strength of said battery-current is either increased or diminished. WVhen said current is increased, it acts, on passing through the primary of the coil L, more strongly to magnetize the core; and, conversely,when the current is decreased in strength, the magnetism of the core becomes reduced. It has already been explained that the spring I, which supports the movable electrode,is ofinductive material, is polarized by the permanent magnet J, and that it also forms the armature of the core of the electro-magnet L. It has also been stated that the core K of said electro-magnet L is normally polarized by induction from the permanent magnet N. Now, the pole of the permanent magnet J, which polarizes thearmature-spring I, and the pole of the permanent magnet N, held in contact with the core K, may be of like name. Consequently the core K and its armature I will be of like names, and they will therefore tend to mutual repulsion. This is the polarization in v the instrument shown in the drawings. \Vhen, by reason of the movement of the electrodes, a stronger current enters the primary of the coil L, the core is more strongly magnetized, and the pole repels its armature of like name more strongly, and thus presses the electrodes more closely together. .Vhen, by the movement of the electrodes, the current entering the primary of the coil Lis reduced in strength, then the core is not so highly magnetized, and the electrodes will thus be less strongly pressed together. The coil L therefore serves as a means of regulating the pressure between the electrodes in accordance with the movements of the diaphragm. In other words, it will be apparent, first, that, normally, the armature and pole of the core mutually repel, by reason of their magnetism being of the same name; second, that as the armature moves toward the pole by reason of the pressure of the diaphragm upon the electrodes, a stronger current energizes the core still to repel; and, third, that this repulsion augments in proportion to the movement of the armature toward the pole, and as the local-battery current passes through theprimary of said coil, it follows that induced currents are set up in the secondary wire also forming part of the coil.

I claim as my invention 1. In a telephone-transmitter, a diaphragm, an electrode supported by or otherwise connected so as to vibrate with said diaphragm, a second electrode sustained by a permanentlypolarized vibratory support of inductive material in contact with the first electrode, the said support forming the armature of an electro-magnet having a permanently-polarized core, the contiguous ends of said armature and core being of like polarity, and the said electrodes and the coil of the clectro-magnet being in circuit, substantially as described.

2. Ina telephone, and in combination with the diaphragm thereof, and with an electrode supported by or vibrating with said diaphragm, a resistance-varyin g electrode mounted upon avibratory polarized armature whose outward motion is resisted by a fixed polarized magnet, like poles being opposed, the power of the fixed magnet being varied in proportion to the strength of the current passing through a circuit in which is included both electrodes and a coil surrounding the fixed magnet, substantially as described.

3. I11 a telephone, the combination of the diaphragm carrying one electrode, the vibrating electrode supported upon a polarized armature, the polarized magnet in the rear of the armature, the batterycoil, and circuitconnections, whereby the outward motion of the armature and its associated electrode is resisted by the polarized magnet with a force greater in proportion to the appro'ach, and at the same time the power of the magnet is augmented in proportion to the pressure upon the electrodes incident to the increased contact produced by the motion of the diaphragm toward its associated electrode.

4. In a telephone-transmitter, a diaphragm or sound-receiving surface, an electrode supported by or otherwise connected so as to vibrate with said diaphragm, a second electrode sustained by a vibratory elastic support, a permanent magnet connected to and polarizing said support, a means of moving said magnet, and thereby the support, so as to adjust the initial pressure between the electrodes, and an electro-magnet actin upon said support, and included in circult with the electrodes, substantially as described.

5. A telephone-transmitter containing an electrode supported by or vibrating with the diaphragm, and a second electrode supported upon a vibratory permanently-polarized armature, the said armature being arranged in front of the permanently-polarized core of an electro-magnet, two independent means of varying the initial pressure between said electrodes, one of said means consisting inascrew or analogous contrivance for moving the armature and its associated electrode, and the other of said means consisting in a device for moving the core of the electro-magnet nearer to orv farther from the armature, and thereby causing said core to exercise a greater or less magnetic influence thereon, substantially as described.

6. In a telephone containing a diaphragm and a [fixed electrode carried thereby or vibrating therewith, a vibratory electrode sup ported by an armature of inductive material, with a means of mechanically adjusting said armature, and also a means of magnetically adjusting said armature by the approach or recession of the pole of a permanent magnet, either or both of said means of adjustment of the armature operating to vary the initial pressure between the electrodes, substantially as described.

7. In a telephone, the combination of the diaphragm or other vibrating surface carry ing an electrode, the opposing electrode supported upon an armature attached to one pole of a permanent magnet, and magnetized by induction therefrom, and the induction-coil supported upon and having its core magnetized by induction from another permanent magnet, and circuit-connections, substantially as described. 1

S. In a telephone containing circuit-connections, adiaphragm or sound-receiving surface, and an electrode carried by orvibrating with said diaphragm, an electrode having a vibratory support of inductive material polarized by a permanent magnet, the said support being placed in the magnetic field of a second permanent magnet, which second magnet constitutes the core of an induction-coil, substantially as described.

9. In a telephone, the combination of the diaphragm carrying an electrode, the polarized armature carrying a second electrode in contact with the first, the circuit-connections, I

and the induction-coil, whose core, polarized by induction, is located in line with the electrodes, and facing the armature to which one of said electrodes is attached. substantially as described,

10. The pivoted permanent magnet supporting the induction-coil and means for adj usting the same, in combination with the adj ustable permanent magnet provided with a spring of inductive material carrying an electrode, and the diaphragm carrying a second electrode, substantially as described.

. DANIEL DRANVBAUGH. \Vitnesses:

FRED. M. Orr, M. XV. J ACOBS. 

